In the normal operation of railroad, it is often necessary to move a car, locomotive, or entire train from one track to another. If the train is to continue on, this is typically performed using a turnout that enables the train to be moved from one line to the other. however, sometimes in emergency situations it is necessary to derail the train or car off the track to prevent fouling of the mainline or other protected track, in order to prevent significant damage. Examples of such situations include when a train or unattended car is approaching a raised drawbridge, intersections with other rail lines or roadways, or when train crews are working, dead ends, and the like.
With such locations, a double point derail switch is purposely provided to for its ability to derail a train or unattended car. As the name implies, the switch derails the train to prevent entry to foul a main or protected track . A standard double point derail switch uses a normally closed switch for train traffic to continue unaltered on a mainline track. When derailing is required, the switch is opened the same as it would be if it was required to divert a train to another track and the train or car is routed onto a short truncated section and thus derailed so as to protect fouling a mainline or other protected track. However, because one switch point, when closed, sits above the main track, a train passing the double point derail switch experiences a bump and some crosslevel condition when traversing the switch. Further, because the switch is in the path of mainline train traffic during normal use, the switch requires routine maintenance even though it may never be activated for use as a derailer.
U.S. Pat. No. 463,727 (the '727 patent) issued Nov. 24, 1891 describes a switch which lifts a train car wheel over the active track. However, the way the switch rail in the '727 patent is constructed is impractical to produce and too costly to deploy.